The present invention relates to an esterified product excellent in lubricating properties and the product can be used as metal working oils and metal plastic working oils such as rolling mill oils, cutting oils, grinding oils, drawing oils and press working oils. In particular, the present invention relates to a rolling mill oil having a low friction coefficient and excellent in pressure resistance under high pressure and high speed rotational conditions. In addition, the present invention further relates to a lubricant which shows excellent properties in metal plastic workings such as cutting working, grinding working, drawing working and press working of metals.
In recent years, the use conditions of lubricating oils have been more and more severer in response to a rapid development in various mechanical industries and hence superior lubricating properties have correspondingly been required for the oils.
Rolling mill oils conventionally used are roughly classified into the following three groups: oils and fats type rolling mill oils containing animal and/or plant oils and fats such as beef tallow, lard, palm oil and rape oil as base oils thereof; mineral oil type rolling mill oils and those comprising a mixture of mineral oils and oils and fats. In recent years, the development of high-speed rolling and high pressure rolling has been directed to further saving of energy and to improvement in the production efficiency. Rolling mill oils comprising animal and plant oils and fats as the base oils thereof are in general though to be suitable for a high-load and high-speed rolling, but there have practically been required for the development of rolling mill oils having further improved properties along with the recent development of techniques for rolling at a super-high-speed and under a super-high-pressure.
Moreover, if animal and plant oils and fats are used as the base oils in cold rolling working and a steel sheet subjected to such cold rolling is directly annealed without removing oil substances adhered to the surface of the steel sheet, the surface of the steel sheet is contaminated during the annealing process. On the other hand, if a rolling mill oil containing mineral oils as the base oils thereof is used, such rolling mill oils do not show high-speed and high-pressure rolling properties.
Although synthetic ester oils are recently developed (see, for instance, Japanese Patent Publication for Opposite Purpose (hereunder referred to as "J. P. KOKOKU") Nos. Sho 57-27156 and 60-54355; JANKATSU (Lubrication) 32, No. 2; and ibid 27, No. 8), the development of rolling mill oils having further improved properties have been desired taking into consideration rolling operations under more higher pressure and more faster rolling speed conditions.
On the other hand, the lubricants used in cutting working and grinding working of metals comprise a proper mixture of components selected, depending on purposes, from the group consisting of mineral oils, animal and plant oils and fats, extreme pressure additives, surfactants, antifoaming agents, anticorrosive agents for metals, antioxidants, antiseptics and antifungal agents. Cutting lubricants are usually used after diluting them 10 to 100 times with water, but water-insoluble cutting lubricants are also used in some cases.
The fundamental characteristics which cutting or grinding oils must have are lubricating properties, cooling properties, rust proof properties and other incidental conditions such as those free of foaming properties, hand-roughening properties, toxicity to men and beasts and giving out of bad smells. Although cutting or grinding oils are varied in the manner of laying stress on what properties they should have, depending on their use purposes and use conditions, they must have the aforementioned properties in a well-balanced manner. However, conventional cutting or grinding oils could not satisfy the aforementioned conditions.